Issue with Receiver condition in ICO object in SAP PI 7.31

Hi Experts,

We have a HTTP_AAE ->PI->SOAP (2 web services as receivers- Receiver1 and Receiver2) scenario.

We are trying to do content based routing to the receivers based on some condition, example if one of the field(/ID) value is starting with alphabet don't sent to Receiver1. Other special characters like #,$,% and numbers are valid characters.

Condition - (string(number(/ID))≠ 'NaN').

When trying to give this condition in the ICO object of this scenario, its giving an error in the sender channel when trying to send the data via HTTP client in PI 7.31

Error Details :

Error: ERROR_IN_MODULECHAIN;ERROR_IN_MODULECHAIN, senderChannel: Catching exception calling messaging system.

The same condition works fine atleast to validate Non-alphabet character in the normal Receiver determination(standard RD).

Kindly provide your inputs/suggestion as to why this condition is failing in ICO and working fine in RD.

Thanks in Advance,

Komal